Solid-state imaging device, method of manufacturing solid-state imaging device, and electronic apparatus

ABSTRACT

A solid-state imaging device according to the present disclosure includes: a semiconductor base; a photoelectric conversion element provided in the semiconductor base; a photoelectric conversion film arranged on a light receiving surface side of the semiconductor base; a contact section to which a signal charge generated in the photoelectric conversion film is read, the contact section being provided in the semiconductor base; a first film member covering the photoelectric conversion element; and a second film member provided on the contact section.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/409,707, filed Dec. 19, 2014, which is a national stage applicationunder 35 U.S.C. 371 and claims the benefit of PCT Application No.PCT/JP2013/066708 having an international filing date of Jun. 18, 2013,which designated the United States, which PCT application claimed thebenefit of Japanese Patent Application No. 2012-146499 filed Jun. 29,2012, the entire disclosures of which are incorporated herein byreference.

TECHNICAL FIELD

The present technology relates to a solid-state imaging device, to amethod of manufacturing a solid-state imaging device, and to anelectronic apparatus.

BACKGROUND ART

For a back-illumination-type solid-state imaging device, there isproposed to form a film having a negative fixed charge on a surface of asemiconductor base in order to suppress generation of dark current thatresults from an interface state of the semiconductor base on a secondsurface side which light enters (for example, see Patent Literature 1).Due to an electric filed induced by the film having the negative fixedcharge, a hole accumulation (hole accumulation) layer is formed on aninterface, of a light receiving section, on a light receiving surfaceside. Generation of an electron from the interface is suppressed by thishole accumulation layer. Also when a charge (an electron) is generatedfrom the interface, the electron demises in the hole accumulation layerin the way of diffusion, and dark current is therefore allowed to bereduced.

Moreover, when this film having the negative fixed charge is formed onthe entire pixel region section and the entire peripheral circuitsection, on the second surface side of the semiconductor base, in theback-illumination-type solid-state imaging device, a potentialdifference is generated between the device on a first surface side ofthe peripheral circuit side and the second surface side of thesemiconductor base. In this case, an unexpected carrier flows from thesemiconductor interface on the second surface side into the device onthe first surface side, which causes malfunction of a circuit.Accordingly, in order to avoid this malfunction, it is proposed tochange a thickness of an insulating film that is formed between the filmhaving the negative fixed charge and the semiconductor base in the pixelsection and the peripheral circuit section (for example, see PatentLiterature 2). For example, it is proposed to form, in the peripheralcircuit section, the insulating film so that a distance from the filmhaving the negative fixed charge to the first surface side of asemiconductor layer is longer than that in the pixel section.

CITATION LIST Patent Literature

Patent Literature 1: Japanese Unexamined Patent Application PublicationNo. 2008-306154

Patent Literature 2: Japanese Unexamined Patent Application PublicationNo. 2010-226143

SUMMARY OF THE INVENTION

As described above, for a back-illumination-type solid-state imagingdevice, it is demanded to improve imaging characteristics of thesolid-state imaging device by preventing generation of dark current orgeneration of unexpected carrier in a semiconductor base interface.

Accordingly, it is desirable to provide a solid-state imaging device andan electronic apparatus that are capable of improving imagingcharacteristics.

A solid-state imaging device of an embodiment of the present technologyincludes: a semiconductor base; a photoelectric conversion elementprovided in the semiconductor base; and a photoelectric conversion filmarranged on a light receiving surface side of the semiconductor base.Further, the solid-state imaging device includes: a contact section towhich a signal charge generated in the photoelectric conversion film isread and that is provided in the semiconductor base; a first film membercovering the photoelectric conversion element; and a second film memberprovided on the contact section.

Moreover, a solid-state imaging device of an embodiment of the presenttechnology includes: a semiconductor base; a photoelectric conversionelement provided in the semiconductor base; a first film member providedon the photoelectric conversion element; and the second film memberprovided on the semiconductor base in an inter-pixel region between thephotoelectric conversion elements adjacent to each other.

Moreover, an electronic apparatus of an embodiment of the presenttechnology includes the above-described solid-state imaging device, anda signal processing circuit configured to process an output signal ofthe solid-state imaging device.

A method of manufacturing a solid-state imaging device of an embodimentof the present technology includes a step of forming a photoelectricconversion element and a contact section in a semiconductor base.Further, the method includes: a step of forming a first film member onthe semiconductor base at a position that covers the photoelectricconversion element; a step of forming a second film member on thesemiconductor base at a position that covers the contact section; and astep of forming a photoelectric conversion film on a light receivingsurface of the semiconductor base.

According to the solid-state imaging device of the embodiment of thepresent technology and according to a solid-state imaging devicemanufactured by the manufacturing method thereof, the first film memberis formed on the photoelectric conversion element, and the second filmmember is formed on the contact section. Alternatively, the first filmmember is formed on the photoelectric conversion element, and the secondfilm member is formed in the inter-pixel region. Accordingly, byselectively forming, on the photoelectric conversion element and on thecontact section or in the inter-pixel region, film members made ofmaterial suitable for characteristics of the respective portions, it ispossible to prevent generation of dark current in the semiconductor baseinterface. As a result, it is possible to improve imagingcharacteristics of the solid-state imaging device.

According to an embodiment of the present technology, it is possible toprovide the solid-state imaging device and the electronic apparatus thatare capable of improving imaging characteristics.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a planar view illustrating a configuration of a solid-stateimaging device of a first embodiment.

FIG. 2 is a planar view illustrating a schematic planar configuration ofthe solid-state imaging device of the first embodiment.

FIG. 3 is a cross-sectional view illustrating a configuration of thesolid-state imaging device of the first embodiment.

FIG. 4 is a manufacturing step diagram of the solid-state imaging deviceof the first embodiment.

FIG. 5 is a manufacturing step diagram of the solid-state imaging deviceof the first embodiment.

FIG. 6 is a manufacturing step diagram of the solid-state imaging deviceof the first embodiment.

FIG. 7 is a manufacturing step diagram of the solid-state imaging deviceof the first embodiment.

FIG. 8 is a manufacturing step diagram of the solid-state imaging deviceof the first embodiment.

FIG. 9 is a manufacturing step diagram of the solid-state imaging deviceof the first embodiment.

FIG. 10 is a cross-sectional view illustrating a configuration of asolid-state imaging device of a second embodiment.

FIG. 11 is a cross-sectional view illustrating a configuration of asolid-state imaging device of a modification of the second embodiment.

FIG. 12 is a cross-sectional view illustrating a configuration of asolid-state imaging device of a third embodiment.

FIG. 13 is a cross-sectional view illustrating a configuration of asolid-state imaging device of a fourth embodiment.

FIG. 14 is a cross-sectional view illustrating a configuration of asolid-state imaging device of a fifth embodiment.

FIG. 15 is a cross-sectional view illustrating a configuration of asolid-state imaging device of a sixth embodiment.

FIG. 16 is a cross-sectional view illustrating a configuration of asolid-state imaging device of a seventh embodiment.

FIG. 17 is a cross-sectional view illustrating a configuration of asolid-state imaging device of an eighth embodiment.

FIG. 18 is a cross-sectional view illustrating a configuration of asolid-state imaging device of a ninth embodiment.

FIG. 19 is a cross-sectional view illustrating a configuration of asolid-state imaging device of a tenth embodiment.

FIG. 20 is a cross-sectional view illustrating a configuration of asolid-state imaging device of an eleventh embodiment.

FIG. 21 is a diagram illustrating a configuration of an electronicapparatus.

MODES FOR CARRYING OUT THE INVENTION

Examples of a best mode for carrying out the present technology isdescribed below. However, the present technology is not limited to theexamples below.

It is to be noted that the description is provided in the followingorder.

1. Summary of Solid-state Imaging Device

2. First Embodiment of Solid-state Imaging Device

3. Method of Manufacturing Semiconductor Unit of First Embodiment

4. Second Embodiment of Solid-state Imaging Device

5. Third Embodiment of Solid-state Imaging Device

6. Fourth Embodiment of Solid-state Imaging Device

7. Fifth Embodiment of Solid-state Imaging Device

8. Sixth Embodiment of Solid-state Imaging Device

9. Seventh Embodiment of Solid-state Imaging Device

10. Eighth Embodiment of Solid-state Imaging Device

11. Ninth Embodiment of Solid-state Imaging Device

12. Tenth Embodiment of Solid-state Imaging Device

13. Eleventh Embodiment of Solid-state Imaging Device

14. Electronic Apparatus

[1. Summary of Solid-State Imaging Device]

First, prior to description of embodiments of a solid-state imagingdevice of the present technology, summary of the solid-state imagingdevice is described. In a back-illumination-type solid-state imagingdevice that includes a film having a negative fixed charge, the filmhaving the negative fixed charge is formed on the entire surface of asemiconductor base in order to suppress generation of dark currentresulting from an interface state of the semiconductor base. In thisstructure, the film having the negative fixed charge is provided notonly on a photoelectric conversion element (a photodiode PD) formed onthe semiconductor base, but also on a separation region (an inter-pixelregion) between adjacent photodiodes PD, on a peripheral circuit sectionin which peripheral circuits are formed, and the like. The solid-stateimaging device having such a structure has some problems.

When a material that has a refractive index smaller than that of thesemiconductor base is used as the film having the negative fixed charge,reflection of incident light is suppressed, and the film having thenegative fixed charge therefore serves as an anti-reflection film. Whena low reflection film is formed on the photoelectric conversion element,this is preferable because sensitivity is increased due toanti-reflection characteristics.

However, when the film having the negative fixed charge that has arefractive index smaller than that of the semiconductor base is formednot only on the photoelectric conversion element but also in an entirepixel region that includes the inter-pixel region, there is an issue ofincrease in color mixture. Specifically, due to the anti-reflectioncharacteristics of the film having the negative fixed charge,sensitivity of the whole of the semiconductor base is increased, and anamount of a signal charge generated in the semiconductor base in theinter-pixel region is also increased. Further, due to increase in signalcharge in the inter-pixel region, an amount of a straying signal chargeis increased, and a flow-in amount to the photoelectric conversionelement is increased. As a result, color mixture is increased. Asdescribed above, increase in color mixture between pixels is an issue inthe solid-state imaging device including the film having negative fixedcharge.

To address the above-described issue of color mixture, for example, itis effective to form a metal light blocking layer in a lattice shape onthe inter-pixel region. However, because the film having the negativefixed charge, the insulating film, and the like are laminated betweenthe semiconductor base and the metal light blocking layer, a distancefrom the metal light blocking layer to the semiconductor base is long.For this reason, light blocking by the metal light blocking layer is notallowed to be performed sufficiently with respect to light that entersfrom an oblique direction. As described above, the configuration thatincludes the film having the negative fixed charge is effective insuppression of dark current and improvement in sensitivity due toprovision of the anti-reflection characteristics in the photoelectricconversion element, but has the issue of color mixture resulting fromincrease in sensitivity in the inter-pixel region.

Also, there is proposed a solid-state imaging device (a laminated-typeimaging device) that has a configuration in which a photoelectricconversion material is provided outside the semiconductor base. In thesolid-state imaging device having this configuration, a contact sectionto which a charge that has been subjected to photoelectric conversion inthe photoelectric conversion material is transferred is formed on asurface on the second surface side of the semiconductor base. The chargethat has been subjected to photoelectric conversion in the photoelectricconversion material is read to a circuit formation surface of thesemiconductor base via this contact section. The contact section may bedesirably configured of a high-concentration impurity region forsuppressing dark current. Also in the solid-state imaging device havingthis configuration, the technique of laminating the film having thenegative fixed charge on the semiconductor surface is effective forsuppressing dark current on the surface of the semiconductor base.

In the laminated-type imaging device, a well having a conductivity typeopposite of that of the contact section is formed around the contactsection. Further, a depletion layer is formed between the contactsection and the well. This depletion layer extends from an interface ofthe contact section and the well in the semiconductor base to thesurface of the semiconductor base that has many carrier generationsources such as the interface state.

For this reason, when the film having the negative fixed charge isformed on the contact section of the imaging device described above, thedepletion layer formed around the contact section expands to the contactsection side. Alternatively, electric field intensity of this depletionlayer is increased. Moreover, by providing the film having the negativefixed charge on the surface of the semiconductor base, the depletionlayer is formed between the contact section and the hole accumulationlayer that is formed in the semiconductor base interface. Accordingly,dark current in the contact section is increased. As described above,the second problem is increase in dark current.

In an embodiment of the present technology, there is proposed aconfiguration that is capable of achieving both suppression of darkcurrent and improvement in sensitivity in the photoelectric conversionelement, and suppression of color mixture in the inter-pixel region, inthe solid-state imaging device that includes the film having thenegative fixed charge. Further, there is proposed a configuration thatis capable of achieving both suppression of dark current in thesemiconductor base interface due to the film having the negative fixedcharge and suppression of dark current in the contact section, in thesolid-state imaging device that has a configuration in which thephotoelectric conversion material is provided outside the semiconductorbase. With the configuration that is capable of achieving bothsuppression of dark current in the semiconductor base interface andsuppression of dark current in the contact section, and suppression ofcolor mixture in the inter-pixel region, or the suppression of darkcurrent in the contact section, the solid-state imaging device superiorin imaging characteristics is configured.

[2. First Embodiment of Solid-State Imaging Device]

[Schematic Configuration of Solid-State Imaging Device]

Description is provided of an embodiment of a solid-state imaging deviceto which the present technology is applied.

FIG. 1 illustrates a schematic configuration of a CMOS-type solid-stateimaging device 1 as an example of the solid-state imaging device towhich the present technology is applied. The configuration in FIG. 1 isa configuration common to solid-state imaging devices according to therespective embodiments described below. Further, in the embodimentsbelow, description is provided of a so-called back-illumination-typeCMOS-type solid-state imaging device in which the opposite (backsurface) side of the circuit formation surface (front surface) side ofthe semiconductor base is configured to serve as a light enteringsurface.

[General Configuration of Solid-State Imaging Device]

FIG. 1 is a schematic configuration diagram illustrating the whole ofthe CMOS-type solid-state imaging device 1 according to a firstembodiment. The solid-state imaging device 1 of the present embodimentexample is configured to include a pixel region 3, a vertical drivecircuit 4, a column signal processing circuit 5, a horizontal drivecircuit 6, an output circuit 7, a control circuit 8, etc. The pixelregion 3 is configured of a plurality of pixels 2 that are arranged on asemiconductor base 11.

The pixel 2 is configured of a photodiode that is the photoelectricconversion element, and a plurality of pixel transistors. The pluralityof pixels 2 are arranged, on the semiconductor base 11, regularly in atwo-dimensional array. The pixel transistors configuring the pixel 2 maybe four pixel transistors that are configured of a transfer transistor,a reset transistor, a selection transistor, and an amplifier transistor,or may be three transistors excluding the selection transistortherefrom.

The pixel region 3 is configured of the plurality of pixels 2 that arearranged regularly in a two-dimensional array. The pixel region 3 isconfigured of an effective pixel region and a black reference pixelregion (not illustrated). The effective pixel region amplifies a signalcharge that has been generated by actual light reception andphotoelectric conversion thereon and reads the amplified charge to thecolumn signal processing circuit 5. The black reference pixel region isfor outputting optical black that serves as a reference of black level.The black reference pixel region is typically formed in an outerperipheral portion of the effective pixel region.

The control circuit 8 generates a clock signal, a control signal, etc.that serve as references of operations of the vertical drive circuit 4,the column signal processing circuit 5, the horizontal drive circuit 6,etc., based on a vertical synchronization signal, a horizontalsynchronization signal, and a master clock. Further, the clock signal,the control signal, etc. generated by the control circuit 8 are inputtedto the vertical drive circuit 4, the column signal processing circuit 5,the horizontal drive circuit 6, etc.

The vertical drive circuit 4 may be configured, for example, of a shiftregister, and selectively and sequentially scans the respective pixels 2in the pixel region 3 on a row unit basis in a vertical direction.Further, the vertical drive circuit 4 supplies, to the column signalprocessing circuit 5 via a vertical signal line 9, a pixel signal basedon the signal charge that has been generated in accordance with a lightreception amount in the photodiode in each of the pixels 2.

The column signal processing circuit 5 may be arranged, for example, foreach column of the pixels 2. The column signal processing circuit 5 mayperform, for each pixel column, a signal process such as noise removaland signal amplification on the signals outputted from the pixels 2corresponding to one row, in response to a signal from the blackreference pixel region (which is not illustrated but is formed aroundthe effective pixel region). A horizontal selection switch (notillustrated) is arranged between an output stage of the column signalprocessing circuit 5 and a horizontal signal line 10.

The horizontal drive circuit 6 may be configured, for example, of ashift resistor. The horizontal drive circuit 6 sequentially outputshorizontal scanning pulses to select the respective column signalprocessing circuits 5 in order, and allows pixel signals to be outputtedfrom the respective column signal processing circuits 5 to thehorizontal signal line 10. The output circuit 7 performs a signalprocess on the signals that are sequentially supplied from therespective column signal processing circuits 5 via the horizontal signalline 10 and outputs the processed signals.

[Configuration of Main Part of Solid-State Imaging Device (Planar View)]

FIG. 2 illustrates a schematic planar configuration in the unit pixel 2in the solid-state imaging device. The unit pixel 2 is configured of aphotoelectric conversion region and a charge reading section. In thephotoelectric conversion region, first to third photoelectric conversionelements that each perform photoelectric conversion on light having awavelength of red (R), green (G), or blue (B) are laminated in threelayers. The charge reading section corresponds to each of thephotoelectric conversion elements. In the present embodiment example,the photoelectric conversion region is configured of the firstphotoelectric conversion element and the second photoelectric conversionelement that are formed in the semiconductor base, and the thirdphotoelectric conversion element (a photoelectric conversion film) thatis formed on the light receiving surface of the semiconductor base.Moreover, the photoelectric conversion region is provided with animpurity diffusion region 13 connected to the first photoelectricconversion element, an impurity diffusion region 12 connected to thesecond photoelectric conversion element, and an impurity diffusionregion 14 connected to the third photoelectric conversion element (thephotoelectric conversion film). The charge reading section is configuredof first to third pixel transistors TrA, TrB, and TrC that correspond tothe first to third photoelectric conversion elements, respectively. Inthe solid-state imaging device 1, light is separated in a verticaldirection in the unit pixel 2.

The first to third pixel transistors TrA, TrB, and TrC are formed in theperiphery of the photoelectric conversion regions, and are eachconfigured of four MOS-type transistors. The first pixel transistor TrAis configured of a first transfer transistor Tr1, a reset transistorTr4, an amplifier transistor Tr5, and a selection transistor Tr6 thatoutput, as a pixel signal, a signal charge that is generated andaccumulated in the first photoelectric conversion element describedlater. The second pixel transistor TrB is configured of a secondtransfer transistor Tr2, a reset transistor Tr7, an amplifier transistorTr8, and a selection transistor Tr9 that output, as a pixel signal, asignal charge that is generated and accumulated in the secondphotoelectric conversion element described later. The third pixeltransistor TrC is configured of a third transfer transistor Tr3, a resettransistor Tr10, an amplifier transistor Tr11, and a selectiontransistor Tr12 that output, as a pixel signal, a signal charge that isgenerated and accumulated in the third photoelectric conversion element(the photoelectric conversion film) described later.

The first transfer transistor Tr1 is configured of a floating diffusionsection FD1 and a transfer gate electrode 15. The floating diffusionsection FD1 is adjacent to the impurity diffusion region 13 and isformed on the front surface (the first surface) side of thesemiconductor base. The transfer gate electrode 15 is formed on thesemiconductor base 11 with a gate insulating film in between. The secondtransfer transistor Tr2 is configured of a floating diffusion sectionFD2 and a transfer gate electrode 16. The floating diffusion section FD2is adjacent to the impurity diffusion region 12 and is formed on thefront surface (the first surface) side of the semiconductor base. Thetransfer gate electrode 16 is formed on the semiconductor base 11 with agate insulating film in between. The third transfer transistor Tr3 isconfigured of a floating diffusion section FD3 and a transfer gateelectrode 17. The floating diffusion section FD3 is adjacent to theimpurity diffusion region 14 and is formed on the front surface (thefirst surface) side of the semiconductor base. The transfer gateelectrode 17 is formed on the semiconductor base 11 with a gateinsulating film in between.

Moreover, in the back-illumination-type solid-state imaging device, thefront surface (the circuit formation surface) side of the semiconductorbase 11 is provided with the reset transistors Tr4, Tr7, and Tr10, theamplifier transistors Tr5, Tr8, and Tr11, and the selection transistorsTr6, Tr9, and Tr12. The reset transistors Tr4, Tr7, and Tr10 are eachconfigured of source-drain regions 23 and 24 and a gate electrode 20.The amplifier transistors Tr5, Tr8, and Tr11 are each configured ofsource-drain regions 24 and 25 and a gate electrode 21. The selectiontransistors Tr6, Tr9, and Tr12 are each configured of source-drainregions 25 and 26 and a gate electrode 22.

Moreover, in each of these pixel transistors TrA, TrB, and TrC, thefloating diffusion sections FD1, FD2, and FD3 are each connected to onesource-drain region 23 of the corresponding reset transistors Tr4, Tr7,or Tr10. Further, the floating diffusion sections FD1, FD2, and FD3 areconnected to the gate electrodes 21 of the corresponding amplifiertransistors Tr5, Tr8, and Tr11, respectively. Further, the source-drainregions 24 that are shared between the reset transistors Tr4, Tr7, andTr10 and the amplifier transistors Tr5, Tr8, and Tr11 are connected to apower voltage line Vdd. Further, one source-drain region 26 of each ofthe selection transistors Tr6, Tr9, and Tr12 is connected to a selectionsignal line VSL.

[Configuration of Pixel Section of Solid-State Imaging Device]

FIG. 3 illustrates a schematic configuration of the photoelectricconversion region illustrated in FIG. 2. FIG. 3 is a cross-sectionalconfiguration of a main part in the photoelectric conversion region inthe solid-state imaging device. In FIG. 3, only the first to thirdtransfer transistors Tr1, Tr2, and Tr3 in the first to third pixeltransistors TrA, TrB, and TrC are illustrated, and illustration of otherpixel transistors are omitted. The solid-state imaging device of thepresent embodiment is a back-illumination-type solid-state imagingdevice in which light enters from the back surface (the second surface)side opposite from the front surface (the first surface) side of thesemiconductor base 11 on which the pixel transistors are formed. In FIG.4, the upper side of the drawing is set as a light receiving surfaceside, and the lower side is set as the circuit formation surface onwhich the pixel transistors, peripheral circuits such as a logiccircuit, etc. are formed.

The solid-state imaging device illustrated in FIG. 3 includes, as theunit pixel 2, a region in which the first photodiode PD1 and the secondphotodiode PD2 described above, as well as a photoelectric conversionfilm 32 and a vertical transfer path 40 are formed. Further, aninter-pixel region 30 is included in a region between the adjacent unitpixels 2.

The solid-state imaging device illustrated in FIG. 3 includes, in thesemiconductor base 1, the first photodiode PD1 and the second photodiodePD2 that serve as the first and second photoelectric conversionelements. Further, the solid-state imaging device illustrated in FIG. 3includes, on the second surface side of the semiconductor base 11, thephotoelectric conversion film 32 that serves as the third photoelectricconversion element. The first photodiode PD1 and the second photodiodePD2 are laminated in a light incidence direction in the semiconductorbase 11, and the photoelectric conversion film 32 is laminated on thefirst photodiode PD1 and the second photodiode PD2.

In such a manner, the solid-state imaging device of the present examplehas a configuration in which the photoelectric conversion film 32, thefirst photodiode PD1, and the second photodiode PD2 are laminated in thelight incidence direction. Further, the photoelectric conversion film32, the first photodiode PD1, and the second photodiode PD2 that arelaminated configure one unit pixel 2.

The first photodiode PD1 and the second photodiode PD2 are formed in awell region (p-Well) 44 in the semiconductor base 11. The semiconductorbase 11 may be configured of silicon or the like and is of a secondconductivity type (an n-type, in the present example). The well region44 is configured of a semiconductor region of a first conductivity type(a p-type, in the present example). The first photodiode PD1 includes ann-type semiconductor region 45 that is formed on the back surface (thesecond surface) side serving as the light receiving surface of thesemiconductor base 11 and is configured of an impurity of the secondconductivity type (the n-type, in the present example). The secondphotodiode PD2 is configured of an n-type semiconductor region 46 thatis formed on the front surface (the first surface) side of thesemiconductor base 11. Further, a p-type semiconductor region(illustration thereof is omitted) having high concentration that servesas the hole accumulation layer is formed in the interface of thesemiconductor base 11 on the front surface (the first surface) side ofthe n-type semiconductor region 46.

Moreover, the transfer gate electrode 15 and the floating diffusionsection FD1 are formed adjacent to the first photodiode PD1 to configurethe first transfer transistor Tr1. The transfer gate electrode 15 isformed, with the gate insulating film in between, in a trench that isformed from the first surface side of the semiconductor base 11 to thevicinity of the n-type semiconductor region 45. The floating diffusionsection FD1 is formed on the first surface side of the semiconductorbase 11. A charge is transferred by the transfer gate electrode 15 tothe floating diffusion section FD1 on the front surface of thesemiconductor base 11.

The floating diffusion section FD2 and the transfer gate electrode 16are formed adjacent to the second photodiode PD2 to configure the secondtransfer transistor Tr2. The transfer gate electrode 16 is formed on thefront surface of the semiconductor base 11 with a gate insulating filmin between. Further, the floating diffusion section FD2 is formed on thefront surface of the semiconductor base 11 with the transfer gateelectrode 16 between the floating diffusion section FD2 and the secondphotodiode PD2.

The photoelectric conversion film 32 is formed on a second film member36 on the back surface (the second surface) side of the semiconductorbase 11. Further, a top electrode 33 and a bottom electrode 31 areformed on both of the upper and lower surfaces of the photoelectricconversion film 32. The top electrode 33 and the bottom electrode 31 areconfigured of an optically-transmissive material. Also, a planarizationlayer 38 is formed on the top electrode 33. Further, an on-chip lens 39is formed on the planarization layer 38.

The first photodiode PD1 and the second photodiode PD2 performphotoelectric conversion on light having different wavelengths dependingon a difference in absorption coefficient. Charges generated in thefirst photodiode PD1 and the second photodiode PD2 are accumulated inthose regions, and are then outputted to the outside by the readingcircuit. The second photodiode PD2 that is formed in a region farthestfrom the light receiving surface serves as a photoelectric conversionelement that performs photoelectric conversion on light having a redwavelength. The first photodiode PD1 formed on the light receivingsurface side serves as a photoelectric conversion element that performsphotoelectric conversion on light having a blue wavelength. Further, thephotoelectric conversion film 32 arranged on the back surface of thesemiconductor base 11 serves as a photoelectric conversion element thatperforms photoelectric conversion on light having a green wavelength.

When used as the photoelectric conversion element that performsphotoelectric conversion on light having the green wavelength, thephotoelectric conversion film 32 may be configured, for example, of anorganic photoelectric conversion material that includes arhodamine-based pigment, a merocyanine-based pigment, quinacridone, orthe like. Further, the top electrode 33 and the bottom electrode 31 areconfigured of an optically-transmissive material, and may be configured,for example, of a transparent conductive film such as an indium-tin(ITO) film or an indium-zinc oxide film.

It is to be noted that the photoelectric conversion film 32 may beconfigured of a material that performs photoelectric conversion on lighthaving a wavelength of blue or red, and the first photodiode PD1 and thesecond photodiode PD2 may be configured to correspond to otherwavelengths. For example, when blue light is absorbed in thephotoelectric conversion film 32, the first photodiode PD1 formed on thelight receiving surface side of the semiconductor base 11 may be set asa photoelectric conversion element that performs photoelectricconversion on green light. Further, the second photodiode PD2 may be setas a photoelectric conversion element that performs photoelectricconversion on red light. Alternatively, when red light is absorbed inthe photoelectric conversion film 32, the first photodiode PD1 formed onthe light receiving surface side of the semiconductor base 11 may be setas a photoelectric conversion element that performs photoelectricconversion on blue light. Further, the second photodiode PD2 may be setas a photoelectric conversion element that performs photoelectricconversion on green light. A photoelectric conversion film that performsphotoelectric conversion on blue light may be configured, for example,of an organic photoelectric conversion material that includes a coumaricacid pigment, tris-8-hydroxyquinoli Al (Alq3), a merocyanine-basedpigment, or the like. Further, a photoelectric conversion film thatperforms photoelectric conversion on red light may be configured of anorganic photoelectric conversion material that includes aphthalocyanine-based pigment.

In the solid-state imaging device of the present example, light that issubjected to photoelectric conversion in the semiconductor base 11 isset to have the wavelength of blue and the wavelength of red. Further,light that is subjected to photoelectric conversion in the photoelectricconversion film 32 is set to have the wavelength of green. In such aconfiguration, by receiving the wavelength of green which is anintermediate wavelength in the photoelectric conversion film 32, it ispossible to improve spectrum characteristics between the firstphotodiode PD1 and the second photodiode PD2.

A contact plug 34 that runs through the second film member 36 isconnected to the bottom electrode 31 formed on the semiconductor base 11side of the photoelectric conversion film 32. The contact plug 34 isconnected to the vertical transfer path 40 that is formed from the firstsurface side to the second surface side of the semiconductor base 11.

The vertical transfer path 40 is configured of a contact section 41, apotential barrier section 42, and a charge accumulation section 43 thatare formed in the vertical direction from the second surface side to thefirst surface side of the semiconductor base 11. The contact section 41is configured of a high-concentration n-type impurity region that isformed on the second surface side of the semiconductor base 11. Thecontact section 41 is configured to establish ohmic contact with thecontact plug 34. The potential barrier section 42 is configured of alow-concentration p-type impurity region, and serves as a potentialbarrier between the contact section 41 and the charge accumulationsection 43. The charge accumulation section 43 is a region thataccumulates signal charges transferred from the photoelectric conversionfilm 32, and is configured of an n-type impurity region that has lowerconcentration than the contact section 41. Further, a high-concentrationp-type impurity region (illustration thereof is omitted) is formed on anuppermost surface of the semiconductor base 11, and generation of darkcurrent in the interface of the semiconductor base 11 is suppressedthereby.

The floating diffusion section FD3 and the transfer gate electrode 17are formed adjacent to the vertical transfer path 40 to configure thethird transfer transistor Tr3. The transfer gate electrode 17 is formedon the front surface of the semiconductor base 11 with a gate insulatingfilm in between. Further, the floating diffusion section FD3 is formedon the front surface of the semiconductor base 11 with the transfer gateelectrode 17 between the vertical transfer path 40 and the floatingdiffusion section FD3.

An interlayer insulating layer 37 is formed on the first surface of thesemiconductor base 11. The interlayer insulating layer 37 is formed tocover the transfer gate electrodes 15, 16, and 17, other gateelectrodes, etc. that are formed on the semiconductor base 11. Moreover,conductive layers such as a plug and a wiring that are connected to thegate electrode, the floating diffusion section, etc. are formed insidethe interlayer insulating layer 37.

[First Film Member and Second Film Member]

A first film member 51 and the second film member 36 are formed betweenthe second surface side of the semiconductor base 11 and thephotoelectric conversion film 32. The first film member 51 is formedonly on a region in which the first photodiode PD1 and the secondphotodiode PD2 are formed. Further, the second film member 36 is formedto cover a region other than a region covered with the first film memberand to cover a region on the first film member 51. Further, the bottomelectrode 31 and the contact plug 34 are formed inside the second filmmember 36. Further, in the second film member 36, a light blocking layer35 is formed in the inter-pixel region 30.

The first film member 51 may be preferably configured of a film having anegative fixed charge. Examples of the film having the negative fixedcharge may include hafnium oxide, aluminum oxide, zirconium oxide,tantalum oxide, and titanium oxide. Moreover, as a material other thanthe above-mentioned materials, it is also possible to form the filmhaving the negative fixed charge of lanthanum oxide, praseodymium oxide,cerium oxide, neodymium oxide, promethium oxide, samarium oxide,europium oxide, gadolinium oxide, terbium oxide, dysprosium oxide,holmium oxide, thulium oxide, ytterbium oxide, lutetium oxide, yttriumoxide, an aluminum nitride film, a hafnium oxynitride film, an aluminumoxynitride film, or the like. Moreover, two or more films havingnegative fixed charges may be laminated. Moreover, the film having thenegative fixed charge may be added with silicon (Si) or nitrogen (N) inthe film in a range that does not degrade insulation. Its concentrationmay be appropriately determined in a range that does not degradeinsulation of the film. By thus adding silicon (Si) or nitrogen (N), itis possible to increase heat resistance of the film, prevention abilityagainst ion injection during the manufacturing steps, etc.

By providing the film having the negative fixed charge on the firstphotodiode PD1 and the second photodiode PD2, the hole accumulation(hole accumulation) layer is formed in the interface of the firstphotodiode PD1. Due to this hole accumulation layer, generation of anelectron from the interface is suppressed, and further, the generatedelectron demises in the hole accumulation layer. As a result, it ispossible to suppress dark current in the solid-state imaging device.

Moreover, when a material that has a refractive index smaller than thatof the semiconductor base 11 is used as the film having the negativefixed charge, the film having the negative fixed charge serves as ananti-reflection film. Accordingly, when the film having the negativefixed charge to be a low reflection film is formed on the firstphotodiode PD1 and the second photodiode PD2, sensitivity of thesolid-state imaging device is improved.

The second film member 36 may be formed of a material different fromthat of the first film member 51 described above. The second film member36 may be made of a material that is used as an interlayer insulatingfilm in a typical semiconductor unit. For example, the second filmmember 36 may be configured, for example, of an oxide film, a nitridefilm, an oxynitride film, or the like, of silicon.

The second film member 36 is formed on the semiconductor base 11 in theinter-pixel region 30. For this reason, when the material that has arefractive index smaller than that of the semiconductor base 11 is used,an amount of light incident on the inter-pixel region 30 of thesemiconductor base 11 is increased, and an amount of signal chargegenerated in the inter-pixel region 30 is increased. This may be a causefor color mixture between pixels. Accordingly, as the second film member36, a material that has a refractive index higher than that of the firstfilm member 51 may be preferably used. Moreover, the second film member36 may be preferably made of a material that has a refractive indexhigher than that of the semiconductor base 11.

Moreover, the second film member 36 is also formed on the contactsection 41. A depletion layer is formed in an interface of the contactsection 41 and the p-well 44 around the contact section 41. Thedepletion layer is also formed on the surface of the second surface ofthe semiconductor base 11. Accordingly, when the first film memberconfigured of the film having the negative fixed charge is formed on thedepletion layer in the interface of the contact section 41 and thep-well 44, the p-type of the p-well 44 is enhanced by an electric fieldinduced by the film having the negative fixed charge. In other words,the depletion layer is enhanced compared to a case where the film havingthe negative fixed charge is not formed. Moreover, the depletion layerexpands from the p-well 44 in a direction on the contact section 41side. As a result, an amount of dark current that flows from thedepletion layer to the contact section 41 is increased.

Accordingly, as the second film member 36 formed on the contact section41, a material that has a negative fixed charge amount smaller than thatof the first film member is used. By using the material that has a smallnegative fixed charge amount, enhancement and expansion of the depletionlayer in the interface of the contact section 41 is allowed to besuppressed by the second film member 36. In particular, a material thatis less likely to generate an interface state between the semiconductorbase 11 made of silicon, for example, an oxide film formed as a resultof reaction with silicon or the like may be preferably used. Due to thisconfiguration, it is possible to suppress dark current in the contactsection 41. It is to be noted that the second film member 36 may bepreferably formed, in addition to the region on the contact section 41,also on a region in which the depletion layer expands in the interfaceof the contact section 41 and the p-well 44. By not forming the firstfilm member 51 configured of the film having the negative fixed chargeon the depletion layer, it is possible to further suppress dark current.

As illustrated in FIG. 3, when the same second film member 36 is formedin the inter-pixel region 30 and on the contact section 41, the secondfilm member 36 may be preferably configured of a material that iscapable of suppressing color mixture in the inter-pixel region 30 and ofsuppressing dark current in the contact section 41 as described above.In other words, as the second film member 36, a material that has ahigher refractive index and a smaller negative fixed charge amount thanthe first film member 51 may be preferably used.

As described above, in the solid-state imaging device of the presentexample, the first film member configured of the film having thenegative fixed charge is selectively formed only on the photodiode PD.Further, the second film member made of a material different from thatof the first film member is formed in a region excluding the region onthe photodiode PD. Due to this configuration, it is possible to suppressdark current by the film having the negative fixed charge in thephotodiode PD. Moreover, it is possible to prevent an unfavorablefunction caused by the film having the negative fixed charge in a regionother than the photodiode PD.

In particular, when a material that has a refractive index higher thanthose of the first film member and the semiconductor base is used as thesecond film member that has the above-described configuration, it ispossible to suppress color mixture caused by the photoelectricconversion in the inter-pixel region. Moreover, when a material that hasa negative fixed charge weaker than that of the first film member isused as the second film member that has the above-describedconfiguration, it is possible to suppress dark current in the contactsection.

It is to be noted that the first film member configured of the filmhaving the negative fixed charge may be present or absent in theperipheral circuit region provided adjacent to the pixel region in thesolid-state imaging device that has the above-described configuration.However, taking into consideration, the function of the film having thenegative fixed charge, on the peripheral circuits, a configuration inwhich the first film member is not provided as in the inter-pixel regionmay be preferable.

Moreover, in the above-described embodiment, the photoelectricconversion film 32 provided as the third photoelectric conversionelement may be configured of a charge retention section that is capableof retaining an electron as with a condenser. In the above-describedpresent embodiment and respective embodiments described later,description is provided of an example of the present technologyreferring to the configuration in which the photoelectric conversionfilm 32 is provided in the third photoelectric conversion element.However, by substituting the charge retention section for thisphotoelectric conversion element, a configuration provided with thecharge retention section may be adopted.

[3. Method of Manufacturing Semiconductor Unit of First Embodiment]

Next, description is provided of a method of manufacturing thesolid-state imaging device of the first embodiment described above.FIGS. 4 to 9 are manufacturing step diagrams of the solid-state imagingdevice of the first embodiment, and in particular, diagrams thatillustrate manufacturing steps in a region in which the photoelectricconversion elements are formed.

First, as illustrated in FIG. 4, the p-well 44 is formed at apredetermined position of the semiconductor base 11. Further, thecontact section 41 and the charge accumulation section 43 that configurethe vertical transfer path 40 are formed at predetermined positions inthe p-well 44. Further, the n-type semiconductor region configuring thefirst photodiode PD1 and the n-type semiconductor region configuring thesecond photodiode PD2 are formed in the same step of forming thevertical transfer path 40. As the semiconductor base, for example, anSOI (Silicon on Insulator) substrate or the like may be used. Also, thetransfer gate electrodes 15, 16, and 17 are formed on the first surfaceside of the semiconductor base 11 with an unillustrated gate oxide filmin between. Further, the floating diffusion sections FD1, FD2, and FD3are formed. After ion injection, an annealing process is performed. Aregion for ion injection is designed taking into consideration diffusioncaused by the annealing process. The ion injection may be performed tobe divided in a plurality of times. Further, the interlayer insulatinglayer 37 is formed on the front surface of the semiconductor base 11.Thereafter, an unillustrated support substrate, another semiconductorbase, or the like may be joined on the first surface side of thesemiconductor base 11, and the resultant is vertically inverted.Further, the semiconductor base 11 is separated from the oxide layer toexpose the second surface side. Each of the configurations in thesemiconductor base 11 illustrated in FIG. 4 may be formed by atechnology used in a typical CMOS process such as ion injection or CVDthat has been publicly known.

Next, as illustrated in FIG. 5, the first film member 51 is formed onthe second surface side of the semiconductor base 11. The first filmmember 51 is formed on the entire surface on the second surface side ofthe semiconductor base 11. As the first film member 51, theabove-described film having the negative fixed charge is used. The firstfilm member 51 may be a single layer, or may be a lamination of aplurality of layers. Further, as illustrated in FIG. 6, a photoresist 52is formed on the first film member 51 as illustrated in FIG. 6. Further,the photoresist in a region other than the region in which thephotodiode PD is formed is removed by a photolithography step ofexposure and development. Further, the first film member 51 exposed fromthe photoresist 52 is removed by dry etching or wet etching. The firstfilm member 51 is thus patterned as illustrated in FIG. 7.

Next, as illustrated in FIG. 8, the second film member 36 is formed tocover the first film member 51 and the second surface side of thesemiconductor base 11. As the second film member 36, for example, aninsulating layer may be formed by an HDP-CVD method or the like.Further, the light blocking layer 35 is formed on the second film member36. The light blocking layer 35 is formed in the inter-pixel region.Further, the contact plug 34 connected to the contact section 41 isformed in the second film member 36. For the contact plug 34, a contacthole is formed by opening a predetermined position in the second filmmember 36. Further, a barrier metal film is formed on a sidewall and abottom surface of the contact hole and a metal material is brought tofill in to form the contact plug 34. The contact plug 34 may beconfigured, for example, of a laminated film of titanium (Ti) andtitanium nitride (TiN) as the barrier metal film, and tungsten (W) as afilling metal material in order to achieve ohmic contact with thecontact section 41.

Moreover, as illustrated in FIG. 9, after laminating the second filmmember 36, the bottom electrode 31 connected to the contact plug 34 isformed. As a transparent electrode that is the bottom electrode 31, forexample, an ITO film having a thickness of about 100 nm formed by asputtering method may be used. Further, the second film member 36 islaminated to cover the bottom electrode 31, and an opening portion fromwhich the bottom electrode 31 is exposed is formed in this second filmmember 36. Further, the photoelectric conversion film 32 is formed tocover the opening portion. Thereafter, the top electrode 33 is formed onan entire surface of an upper portion of the photoelectric conversionfilm 32. As with the bottom electrode 31, for example, an ITO filmhaving a thickness of about 100 nm formed by a sputtering method may beused also as the top electrode 33. Thereafter, the planarization layer38 and the on-chip lens 39 are formed on an upper portion of the topelectrode 33. The solid-state imaging device of the first embodiment isallowed to be manufactured by the above-described steps.

It is to be noted that, in the step of patterning the first film member51, a hard mask method may be performed that uses an oxide film, siliconnitride, or the like is used, instead of the photoresist, on the firstfilm member 51. For example, an oxide film, silicon nitride, or the likemay be deposited on the first film member 51, and a pattern of the hardmask is formed by photolithography and etching. Further, the first filmmember 51 may be patterned by etching the first film member 51 with theuse of this hard mask. Moreover, the solid-state imaging devices of therespective embodiments described below are also allowed to bemanufactured by combining the manufacturing method described in theabove embodiment and a publicly-known method of manufacturing asemiconductor unit.

[4. Second Embodiment of Solid-State Imaging Device]

Next, a second embodiment of the solid-state imaging device isdescribed. FIG. 10 illustrates a cross-sectional configuration of a mainpart in a photoelectric conversion region of the solid-state imagingdevice of the second embodiment. It is to be noted that a configuration,in the second embodiment, similar to that in the first embodimentdescribed above is designated with the same numeral, and descriptionthereof is omitted.

The solid-state imaging device illustrated in FIG. 10 includes the firstphotodiode PD1 that is formed inside the semiconductor base 11 andserves as a photoelectric conversion element, and the first transfertransistor Tr1 that includes the first photodiode PD1. The firstphotodiode PD1 is configured of an n-type semiconductor region 45 madeof a second-conductivity-type (an n-type, in the present example)impurity formed in the semiconductor base 11. The n-type semiconductorregion 45 is formed in the well region (p-well) 44 in thesecond-conductivity-type (the n-type, in the present example)semiconductor base 11 made of silicon or the like. The well-region 44 isconfigured of a first-conductivity-type (a p-type, in the presentexample) semiconductor region.

A transfer gate electrode 53 is formed on the semiconductor base 11 andadjacent to the first photodiode PD1. Further, the floating diffusionsection FD1 adjacent to the transfer gate electrode 53 is formed on thefront surface of the semiconductor base 11 at a position facing thefirst photodiode PD1. In such a manner, the transfer gate electrode 53and the floating diffusion section FD1 are formed adjacent to the firstphotodiode PD1 on the first surface side of the semiconductor base 11 toconfigure the first transfer transistor Tr1. Moreover, the interlayerinsulating layer 37 is formed on the front surface of the semiconductorbase 11 to cover the transfer gate electrode 53, etc.

Moreover, the first film member 51 and the second film member 36 areformed on the back surface of the semiconductor base 11. The first filmmember 51 is formed in a portion in which the first photodiode PD1 isformed. Further, the second film member 36 is formed to cover a regionon the first film member 51 and a region on the second surface of thesemiconductor base 11 in which the first film member 51 is not formed.

Moreover, the light blocking layer 35 is formed in the inter-pixelregion 30 in the second film member 36. Further, a color filter 56corresponding to the first photodiode PD1 is formed on the second filmmember 36 and the light blocking layer 35 with the planarization layer55 in between. Moreover, the on-chip lens 39 corresponding to the firstphotodiode PD1 is formed on the color filter 56 with the planarizationlayer 38 in between.

The first film member 51 is configured of a film having a negative fixedcharge as in the first embodiment described above. As the film havingthe negative fixed charge, the above-described materials may be used.Further, the planarization layers 38 and 55 and the on-chip lens 39 haveconfigurations similar to those in the first embodiment described above.A color filter similar to that in a solid-state imaging device that hasbeen publicly known is applicable as the color filter 56.

The second film member 36 is formed on the inter-pixel region 30 asillustrated in FIG. 10. Further, the second film member 36 maypreferably cover the back surface of the semiconductor base 11 also inthe peripheral circuit region formed around the pixel region. Becausebeing formed on the inter-pixel region 30, the second film member 36 maybe preferably made of a material that has a refractive index higher thanthat of the first film member 51. Further, the second film member 36 maybe preferably made of a material that has a refractive index higher thanthat of the semiconductor base 11. Further, when the second film member36 is formed on the back surface of the semiconductor base 11 also inthe peripheral circuit region, the second film member 36 may bepreferably made of a material that has a negative fixed charge amountsmaller than that of the first film member 51.

In the present embodiment, as illustrated in FIG. 10, a configuration inwhich the first film member 51 is formed on the photodiode PD and otherregion is covered with the second film member 36 is allowed to beadopted also in a configuration in which the photodiode PD is singularlyformed in the unit pixel 2. Also in this configuration, it is possibleto suppress dark current on the photodiode PD, due to the first filmmember 51 configured of the film having the negative fixed charge.Further, it is possible to suppress color mixture by selectively formingthe first film member 51 only on the photodiode PD, and forming thesecond film member 36, in the inter-pixel region 30, that has arefractive index higher than that of the first film member 51.

[Modification]

Next, a modification of the second embodiment is described. FIG. 11illustrates a configuration of the modification of the solid-stateimaging device of the second embodiment. In the modification, theconfiguration of the photodiode PD formed in the semiconductor base 11is different from that in the above-described second embodiment.

A solid-state imaging device illustrated in FIG. 11 includes the firstphotodiode PD1 and the second photodiode PD2 that serve as the first andsecond photoelectric conversion elements in the semiconductor base 11.The first photodiode PD1 and the second photodiode PD2 are laminated inthe light incidence direction in the semiconductor base 11.

The transfer gate electrode 15 and the floating diffusion section FD1are formed adjacent to the first photodiode PD1 to configure the firsttransfer transistor Tr1. The transfer gate electrode 15 is formed in atrench formed from the first surface side of the semiconductor base 11to a region of the first photodiode PD1 with a gate insulating film inbetween. The floating diffusion section FD1 is formed on the firstsurface side of the semiconductor base 11.

Moreover, the floating diffusion section FD2 and the transfer gateelectrode 16 are formed adjacent to the second photodiode PD2 toconfigure the second transfer transistor Tr2. The transfer gateelectrode 16 is formed on the front surface of the semiconductor base 11with a gate insulating film in between. Further, the floating diffusionsection FD2 is formed on the front surface of the semiconductor base 11with the transfer gate electrode 16 between the second photodiode PD2and the floating diffusion section FD2.

The interlayer insulating layer 37 is formed on the front surface of thesemiconductor base 11 to cover the transfer gate electrode 17, etc.Further, the first film member 51 and the second film member 36 areformed on the back surface of the semiconductor base 11. The first filmmember 51 is formed only on a region in which the first photodiode PD1is formed. Further, the second film member 36 is formed to cover aregion on the first film member 51 and a region on the second surface ofthe semiconductor base 11 in which the first film member 51 is notformed.

Moreover, the light blocking layer 35 is formed in the inter-pixelregion 30 in the second film member 36. Further, the color filter 56corresponding to the first photodiode PD1 is formed on the second filmmember 36 and the light blocking layer 35 with the planarization layer55 in between. Moreover, the on-chip lens 39 corresponding to the firstphotodiode PD1 and the second photodiode PD2 is formed on the colorfilter 56 with the planarization layer 38 in between.

As illustrated in FIG. 11, as in the second embodiment, the presenttechnology is applicable also to the solid-state imaging device that hasa configuration in which the photodiodes PD are laminated. Moreover, thepresent technology is applicable also to a solid-state Imaging devicethat has a configuration in which the photodiodes PD are formed in threelayers in the semiconductor base, as in the second embodiment. An effectsimilar to that in the second embodiment is allowed to be achieved alsoin these configurations by selectively forming the first film member onthe photodiode PD with the use of the first film member and the secondfilm member.

[5. Third Embodiment of Solid-State Imaging Device]

Next, a third embodiment of the solid-state imaging device is described.It is to be noted that the third embodiment described below has aconfiguration similar to that in the first embodiment described aboveexcept for a configuration of film members on the back surface of thesemiconductor base 11. Accordingly, in the description below of thethird embodiment, a configuration similar to that in the firstembodiment is designated with the same numeral and description thereofis omitted.

[Film Member]

A configuration of a solid-state imaging device of the third embodimentis illustrated in FIG. 12. In the solid-state imaging device illustratedin FIG. 12, the first film member 51, the second film member 36, and athird film member 57 are formed on the back surface of the semiconductorbase 11. The first film member 51 is formed only on a region in whichthe first photodiode PD1 and the second photodiode PD2 are formed.Further, the third film member 57 is formed on the first film member 51.The third film member 57 is formed on an entire surface on the firstfilm member 51, and is not formed in a region other than the first filmmember 51.

Moreover, the second film member 36 is formed to cover a region otherthan a region covered with the first film member 51 and the third filmmember 57, and a region on the third film member 57. Moreover, thebottom electrode 31, the contact plug 34, and the light blocking layer35 are formed inside the second film member 36.

The first film member 51 and the third film member 57 may each bepreferably configured of a film having a negative fixed charge. The filmhaving the negative fixed charge may be made of the materials describedabove in the first embodiment. The first film member 51 and the thirdfilm member 57 may be configured of the same material, or may beconfigured of different materials. The first film member 51 and thethird film member 57 may preferably have configurations that havedifferent negative fixed charge amounts. Moreover, the second filmmember 36 may be preferably made of a material similar to that in thefirst embodiment described above.

As illustrated in FIG. 12, on a region in which the photodiode PD isformed, a configuration may be adopted in which the first film member 51and the third film member 57 each configured of the film having thenegative fixed charge are laminated. By forming a plurality of layers offilms having negative fixed charges, an electric field to be applied tothe semiconductor base 11 becomes the sum of electric fields of theplurality of formed films. Accordingly, it is possible to controlintensity of the electric field to be applied to the semiconductor base11 by adjusting a material, a thickness, a forming method, etc. of eachof the first film member 51 and the third film member 57. By adoptingsuch a configuration, it becomes easier to control the electric field tobe applied to the semiconductor base 11, compared to a case where thefilm having the negative fixed charge is formed singularly. Moreover,freedom in selectivity of the configurations of the film members isimproved, which also makes it possible to improve productivity of thesemiconductor base.

[6. Fourth Embodiment of Solid-State Imaging Device]

Next, a fourth embodiment of the solid-state imaging device isdescribed. It is to be noted that the fourth embodiment described belowhas a configuration similar to that in the first embodiment describedabove except for a configuration of film members on the back surface ofthe semiconductor base 11. Accordingly, in the description below of thefourth embodiment, a configuration similar to that in the firstembodiment is designated with the same numeral and description thereofis omitted.

[Film Member]

A configuration of a solid-state imaging device of the fourth embodimentis illustrated in FIG. 13. In the solid-state imaging device illustratedin FIG. 13, a first film member 61, a second film member 62, and a thirdfilm member 63 are formed on the back surface of the semiconductor base11. The first film member 61 is formed on a region in which the firstphotodiode PD1 and the second photodiode PD2 are formed, and on theinter-pixel region 30. Further, the second film member 62 is formedcontinuously on the first film member 61 and on the contact section 41.Moreover, the third film member 63 is formed to cover the second filmmember 62.

The first film member 61 may be preferably configured of a film having anegative fixed charge. The film having the negative fixed charge may bemade of the material described above in the first embodiment. Further, amaterial that is typically used as an interlayer insulating film ofwiring layers in a semiconductor unit may be applied to the third filmmember 63. Further, the bottom electrode 31, the contact plug 34, andthe light blocking layer 35 are formed inside the third film member 63.The contact plug 34 runs through the second film member 62 on thecontact section 41, and is connected to the contact section 41.

The second film member 62 is directly formed on the semiconductor base11 in a region on the contact section 41. A region in which the secondfilm member 62 is formed on the semiconductor base 11 is at least in arange equal to or larger than a range in which the depletion layer isformed in the interface of the contact section 41 and the p-well 44around the contact section 41. Moreover, the second film member 62 maybe preferably configured of a film having a negative fixed charge. Thefilm having the negative fixed charge may be made of the materialdescribed above in the first embodiment. However, the second film member62 may be preferably made of a material that has a negative fixed chargeamount smaller than that of the first film member 61.

In a semiconductor unit having the configuration illustrated in FIG. 13,dark current may be generated also in the contact section 41 due to theinterface state of the surface of the semiconductor base 11.Accordingly, it is possible to suppress dark current from the surface ofthe semiconductor base 11 by forming the film having the negative fixedcharge. However, when the negative fixed charge amount is large, thedepletion layer in the interface of the contact section 41 and thep-well 44 is influenced thereby, and dark current is increased. For thisreason, a material that is capable of suppressing dark current as awhole may be preferably applied as the second film member 62, takinginto consideration a suppression amount of the dark current from thesurface of the semiconductor base 11 and an increase amount of the darkcurrent from the depletion layer in the interface of the contact section41 and the p-well 44.

It is to be noted that, in the present example, the configuration inwhich the first film member 61 and the second film member 62 are formedin the inter-pixel region 30 is described. However, in the inter-pixelregion 30, the configurations of the film members are, allowed to beappropriately selected taking into consideration refractive indices ofthe film members to be formed. For example, the first film member 61 andthe second film member 62 may be formed on the inter-pixel region 30 asin the present example, when the issue of color mixture caused by acharge generated in the inter-pixel region 30 does not occur or occursin a negligible extent. Moreover, when taking into consideration thegeneration of color mixture, a film having a preferable refractive indexmay be appropriately selected from the first to third film members 61,62, and 63 to be formed in the inter-pixel region 30.

[7. Fifth Embodiment of Solid-State Imaging Device]

Next, a fifth embodiment of the solid-state imaging device is described.It is to be noted that the fifth embodiment described below has aconfiguration similar to that in the first embodiment described aboveexcept for a configuration of film members on the back surface of thesemiconductor base 11. Accordingly, in the description below of thefifth embodiment, a configuration similar to that in the firstembodiment is designated with the same numeral and description thereofis omitted.

[Film Member]

A configuration of a solid-state imaging device of the fifth embodimentis illustrated in FIG. 14. In the solid-state imaging device illustratedin FIG. 14, a first film member 64, a second film member 65, a thirdfilm member 66, and a fourth film member 67 are formed on the backsurface of the semiconductor base 11. The first film member 64 is formedonly on a region in which the first photodiode PD1 and the secondphotodiode PD2 are formed. The second film member 65 is formed to covera region on the contact section 41, and a region on the depletion layerthat extends in the interface with the p-well 44 around the contactsection 41. The third film member 66 is formed on the semiconductor base11 in the inter-pixel region 30. Further, the fourth film member 67 isformed to cover a region on the first to third film members 64, 65, and66.

The first film member 64 may be preferably configured of a film having anegative fixed charge. The film having the negative fixed charge may bemade of the material described above in the first embodiment. Further, amaterial that is typically used as an interlayer insulating film ofwiring layers in a semiconductor unit may be applied as the fourth filmmember 67. Further, the bottom electrode 31, the contact plug 34, andthe light blocking layer 35 are formed inside the fourth film member 67.The contact plug 34 runs through the second film member 65 on thecontact section 41, and is connected to the contact section 41.

As in the fourth embodiment, the second film member 65 may be preferablyconfigured of a film having a negative fixed charge. However, the secondfilm member 65 may be preferably made of a material that has a negativefixed charge amount smaller than that of the first film member 64. Byselecting such a film having the negative fixed charge for the secondfilm member 65, it becomes possible to suppress dark current in thecontact section 41. The third film member 66 may be preferablyconfigured of a film having a negative fixed charge as with the firstfilm member 64. By providing the negative fixed charge, dark currentfrom the surface of the semiconductor base 11 is suppressed.

Moreover, the third film member 66 has a refractive index higher thanthat of the first film member 64, which suppresses generation of acharge in the inter-pixel region 30 and makes it possible to suppresscolor mixture. For example, when the semiconductor base 11 is made of Siand the fourth film member 67 configuring the wiring layer is made ofSiO₂, by causing the first film member 64 to have a refractive indexthat is between those of Si and SiO₂, anti-reflection characteristicsdue to the first film member 64 is made effective. Further, by causingthe third film member 66 to have a tropism rate that is similar to orhigher than that of SiO₂, a reflection component in the third filmmember 66 is increased. Accordingly, generation of a charge in theinter-pixel region 30 is suppressed, which makes it possible to suppresscolor mixture.

As described above, the films having negative fixed charges that aremade of different materials may be formed in the respective regions onthe photodiode PD, the inter-pixel region, and the contact section. Byforming the films having the negative fixed charges in all of theregions, it is possible to suppress dark current from the surface of thesemiconductor base 11. Moreover, by selecting, for each of the regions,the material, the thickness, the forming method, etc., so that thenegative fixed charge amount of the film member, the refractive index,etc. are made optimum, suppression of dark current, suppression of colormixture, etc. are achieved.

[8. Sixth Embodiment of Solid-State Imaging Device]

Next, a sixth embodiment of the solid-state imaging device is described.It is to be noted that the sixth embodiment described below has aconfiguration similar to that in the first embodiment described aboveexcept for a configuration of film members on the back surface of thesemiconductor base 11. Accordingly, in the description below of thesixth embodiment, a configuration similar to that in the firstembodiment is designated with the same numeral and description thereofis omitted.

[Film Member]

A configuration of a solid-state imaging device of the sixth embodimentis illustrated in FIG. 15. In the solid-state imaging device illustratedin FIG. 15, a first film member 68, a second film member 69, and a thirdfilm member 71 are formed on the back surface of the semiconductor base11. The second film member 69 is formed on a region in which a depletionlayer is formed in the interface of the contact section 41 and thep-well 44 around the contact section 41. Further, the first film member68 is formed on a region in which the first photodiode PD1 and thesecond photodiode PD2 are formed, and on the second film member 69.Moreover, the third film member 71 is formed to cover a region, on thesemiconductor base 11, in which the first film member 68 is not formed,and a region on the first film member 68.

The first film member 68 may be preferably configured of a film having anegative fixed charge. The film having the negative fixed charge may bemade of the material described above in the first embodiment. Further, amaterial that is typically used as an interlayer insulating film ofwiring layers in a semiconductor unit may be applied as the third filmmember 71. The bottom electrode 31, the contact plug 34, and the lightblocking layer 35 are formed inside the third film member 71. Thecontact plug 34 runs through the first film member 68 and the secondfilm member 69 on the contact section 41, and is connected to thecontact section 41.

The second film member 69 is formed of a material that has a smallinterface state. The second film member 69 may be configured, forexample, of an oxide film that is formed as a result of reaction withthe material of the semiconductor base 11, or the like. Further, thesecond film member 69 is formed to have a thickness that does not giveinfluence of the first film member 68, configured of the film having thenegative fixed charge, on the contact section 41 and the depletion layerformed around the contact section 41.

By forming the second film member 69 on the contact section 41 andbetween a region around the contact section 41 and the first film member68, a configuration is achieved in which the first film member 68 is notin direct contact with the periphery of the contact section 41. Byadopting this configuration, no influence is given on the depletionlayer in the interface of the contact section 41 and the p-well 44around the contact section 41. Accordingly, it is possible to suppressgeneration of dark current from the depletion layer.

Moreover, in a portion covered with the first film member 68, darkcurrent from the surface of the semiconductor base 11 is suppressed dueto the film having the negative fixed charge. Accordingly, it ispossible to suppress dark current from the surface of the semiconductorbase 11 in a formation region of the photodiode PD. Further, by usingthe material that has a small interface state as the second film member69, it is possible to suppress dark current in the periphery of thecontact section 41 covered with the second film member 69. Moreover, inthe inter-pixel region 30, by providing the third film member 71 thathas a refractive index increasing the reflection component, it ispossible to suppress generation of a charge in the inter-pixel region30, and to suppress color mixture.

As described above, in addition to selectively forming the films havingthe negative fixed charge, different kinds of films may be providedbetween the semiconductor base 11 and the films having the negativefixed charge in the respective regions of a region on the photodiode PD,the inter-pixel region, and the contact section.

[9. Seventh Embodiment of Solid-State Imaging Device]

Next, a seventh embodiment of the solid-state imaging device isdescribed. It is to be noted that the seventh embodiment described belowhas a configuration similar to that in the first embodiment describedabove except for a configuration of film members on the back surface ofthe semiconductor base 11. Accordingly, in the description below of theseventh embodiment, a configuration similar to that in the firstembodiment is designated with the same numeral and description thereofis omitted.

[Film Member]

A configuration of a solid-state imaging device of the seventhembodiment is illustrated in FIG. 16. In the solid-state imaging deviceillustrated in FIG. 16, a first film member 72, a second film member 73,and a third film member 74 are formed on the back surface of thesemiconductor base 11. The first film member 72 is formed only on aregion in which the first photodiode PD1 and the second photodiode PD2are formed. The second film member 73 is formed to cover a region on thecontact section 41 and a region on the depletion layer that extends inthe interface with the p-well 44 around the contact section 41. Thethird film member 74 is formed to cover a region, on the semiconductorbase 11, in which the first film member 72 and the second film member 73are not formed, and a region on the first film member 72 and the secondfilm member 73.

The first film member 72 and the second film member 73 are eachconfigured of a conductive layer. The first film member 72 is configuredof a transparent electrode to which a voltage is allowed to be applied.The first film member 72 and the second film member 73 are configured tobe separated from each other with the third film member 74 in between.Further, unillustrated wirings are connected to the respective firstfilm member 72 and second film member 73, which achieves a configurationin which a voltage is allowed to be applied to each of the first filmmember 72 and the second film member 73 independently. The transparentelectrode may be made of the material same as that of the top electrode33 and the bottom electrode 33 described above. Moreover, a materialthat is typically used as a wiring or an electrode in a semiconductorunit may be applied as the second film member 73. In particular, whenthe second film member 73 is formed of a transparent electrode same asthe first film member 72, the first film member 72 and the second filmmember 73 are allowed to be fabricated in the same step. For thisreason, the second film member 73 may be preferably formed of atransparent electrode that is the same as the first film member 72.

A material that is typically used as an interlayer insulating film ofwiring layers in a semiconductor unit may be applied as the third filmmember 74. The bottom electrode 31, the contact plug 34, and the lightblocking layer 35 are formed inside the third film member 74. Aninsulating layer 75 is formed around the contact plug 34, and the secondfilm member 73 and the contact plug 34 are configured not to be incontact with each other.

By configuring each of the first film member 72 and the second filmmember 73 of a conductive layer, generation of an electron from theinterface of the semiconductor base 11 is suppressed when a negativebias is applied to the first film member 72 and the second film member73, which makes it possible to suppress dark current. By applying thenegative bias, the hole accumulation layer is formed on the surface ofthe semiconductor base 11 as in the case of forming the film having thenegative fixed charge, which suppresses dark current.

Moreover, in the present example, separated conductive layers are formedin the respective regions of the region in which the photodiode PD isformed and the region in which the contact section 41 is formed. It istherefore possible to appropriately and independently adjust voltages tobe applied to the respective film members. For example, by causing thevoltage to be applied to the first film member 72 to be higher than thevoltage to be applied to the second film member 73, the holeaccumulation amount in the interface of the semiconductor base 11 on thephotodiode PD is increased, which suppresses dark current. Moreover, bylowering the voltage to be applied to the second film member 73 at thistime, dark current from the interface of the semiconductor base 11around the contact section 41 is suppressed, and an influence on thedepletion layer around the contact section 41 is suppressed to suppressgeneration of dark current resulting from the depletion layer.

As described above, the conductive layers may be selectively formedinstead of the films having the negative fixed charges on the respectiveregions of the region on the photodiode PD and the contact section. Byadopting such a configuration, suppression of dark current, suppressionof color mixture, etc. are achieved.

[10. Eighth Embodiment of Solid-State Imaging Device]

Next, an eighth embodiment of the solid-state imaging device isdescribed. It is to be noted that the eighth embodiment described belowhas a configuration similar to that in the first embodiment describedabove except for a configuration of film members on the back surface ofthe semiconductor base 11. Accordingly, in the description below of theeighth embodiment, a configuration similar to that in the firstembodiment is designated with the same numeral and description thereofis omitted.

[Film Member]

A configuration of a solid-state imaging device of an eighth embodimentis illustrated in FIG. 17. In the solid-state imaging device illustratedin FIG. 17, a first film member 76 and the second film member 36 areformed on the back surface of the semiconductor base 11.

The first film member 76 is formed only on a region in which the firstphotodiode PD1 and the second photodiode PD2 are formed. Further, thesecond film member 36 is formed to cover a region on the depletion layerthat extends in the interface with the p-well 44 around the contactsection 41, and a region that is not covered with the first film memberincluding the inter-pixel region 30, and a region on the first filmmember 51. Moreover, the bottom electrode 31 and the contact plug 34 areformed inside the second film member 36. Further, the light blockinglayer 35 is formed in the inter-pixel region 30 in the second filmmember 36.

The first film member 76 is configured of a semiconductor material thathas a band gap larger than that of the semiconductor base 11. Examplesof the semiconductor material that has a large band gap may include asemiconductor material that includes silicon-carbide-based mixedcrystal, ZnCdSe-based mixed crystal, AlGaInN-based mixed crystal,AlGaInP-based mixed crystal, etc. By using the semiconductor materialthat has a large band gap as the first film member 76, it is possible todecrease probability of generation of dark current as with the holeaccumulation layer induced by the film having the negative fixed charge.Accordingly, by forming, on the photodiode PD, the first film member 76made of the semiconductor material that has a large band gap, it ispossible to suppress dark current from the interface of thesemiconductor base 11.

[11. Ninth Embodiment of Solid-State Imaging Device]

Next, a ninth embodiment of the solid-state imaging device is described.It is to be noted that the ninth embodiment described below has aconfiguration similar to that in the first embodiment described aboveexcept for a shape of the second surface side of the semiconductor base11 and a configuration of film members. Accordingly, in the descriptionbelow of the ninth embodiment, a configuration similar to that in thefirst embodiment is designated with the same numeral and descriptionthereof is omitted.

[Film Member]

A configuration of a solid-state imaging device of a ninth embodiment isillustrated in FIG. 18. In the solid-state imaging device illustrated inFIG. 18, an embedded-type element separation section 77 is formed on thesecond surface side of the semiconductor base 11. Moreover, a first filmmember 78 and a second film member 79 are formed on the back surface ofthe semiconductor base 11.

The element separation section 77 is configured of a groove (a trench)formed by etching the semiconductor base 11 as with STI, and the firstfilm member 78 and the second film member 79 filling the trench.Moreover, the element separation section 77 is formed on a side surfacearound the vertical transfer path 40, and is formed at a position to bein contact with the vertical transfer path 40. Further, the elementseparation section 77 is formed from the second surface side of thesemiconductor base 11 to a depth that is over the contact section 41 andthe potential barrier section 42.

The element separation section 77 is formed from an outer side of outerperiphery of the charge accumulation section 43 to an inner side of theouter periphery of the charge accumulation section 43. The elementseparation section 77 is formed so that the side surface of the contactsection 41 and the potential barrier section 42 and the side surface ofthe upper portion of the charge accumulation section 43 are in contactwith the element separation section 77. Further, the element separationsection 77 is formed so that portion other than a surface in contactwith the vertical transfer path 40 is in contact with the p-well 44around the vertical transfer path 40. In other words, there is achieveda configuration in which the vertical transfer path 40 is exposed fromthe side surface on the inner periphery side of the element separationsection 77, and the p-well 44 is exposed from the side surface on theinner periphery side to the side surface of the trench.

The first film member 78 is formed on a region in which the firstphotodiode PD1 and the second photodiode PD2 are formed. Further, thefirst film member 78 is formed on the p-well 44 that is exposed to theinner surface of the trench in the element separation section 77. Thefirst film member 78 may be preferably configured of a film having anegative fixed charge. The film having the negative fixed charge may bemade of the material described above in the first embodiment.

The second film member 79 is formed to cover a region that is notcovered with the first film member 78, and a region on the first filmmember 78. Specifically, the second film member 79 is formed on a regionon the contact section 41, on a region on the contact section 41, thepotential barrier section 42, and the charge accumulation section 43exposed to the side surface of the trench, and on a region that is notcovered with the first film member 78 including the inter-pixel region30. Further, the second film member 79 is formed to fill the entiretrench in the element separation section 77.

Moreover, a material that is typically used as an interlayer insulatingfilm of wiring layers in a semiconductor unit may be applied as thesecond film member 79. In particular, an insulating film formed of amaterial that has a small interface state and formed by a method thathas a small interface state, for example an oxide film formed as aresult of reaction with Si or the like may be preferably arranged. Thebottom electrode 31, the contact plug 34, and the light blocking layer35 are formed inside the second film member 79. Further, the second filmmember 79 has a configuration similar to that of the second film memberin the first embodiment described above, except for that the second filmmember 79 fills the trench configuring the element separation section77.

In the above-described configuration, there is formed the first filmmember 78 that is configured, of the film having the negative fixedvalue on the semiconductor base 11 in the region in which the photodiodePD is formed and on the p-well 44 in the trench. By providing the filmhaving the negative fixed charge on the photodiode PD, it is possible tosuppress dark current from the interface of the semiconductor base 11.Moreover, in the p-well 44 exposed to the inner surface of the trench,dark current may be generated as a result of insufficiency of theimpurity in this interface. Accordingly, by forming the film having thenegative fixed charge on the p-well 44 in the trench, it is possible tosuppress dark current from the interface of the element separationsection 77.

Moreover, by providing the element separation section 77, theconjunction area of the p-n junction in the contact section 41 isreduced. Accordingly, it is possible to suppress leakage current.Moreover, the first film member 78 is not arranged around the contactsection 41 and in the inter-pixel region 30. By adopting such aconfiguration, suppression of dark current, suppression of colormixture, etc. are achieved.

It is to be noted that, in the above-described embodiment, the firstfilm member configured of the film having the negative fixed charge isformed as a single layer. However, for example, as in the thirdembodiment or the fourth embodiment described above, the first filmmember may be formed of a multi-layer film. Further, the first filmmember may be configured, instead of the film having the negative fixedcharge, of the transparent electrode described above in the seventhembodiment, or the material that has a large band gap described in theeighth embodiment. Moreover, as in the fourth embodiment or the seventhembodiment described above, there may be adopted a configuration inwhich the film having the negative fixed charge, the conductive layers,etc. are formed on the contact section 41 and on the inner surface ofthe trench to which the vertical transfer path 40 is exposed. Also in acase of adopting such a configuration, an effect achieved by theconfiguration in each of the embodiments is achievable in addition tothe effect of the ninth embodiment described above.

[12. Tenth Embodiment of Solid-State Imaging Device]

Next, a tenth embodiment of the solid-state imaging device is described.It is to be noted that the tenth embodiment described below has aconfiguration similar to those in the first embodiment and the ninthembodiment described above except for a configuration of film members onthe back surface of the semiconductor base 11. Accordingly, in thedescription below of the tenth embodiment, a configuration similar tothose in the first embodiment and the ninth embodiment is designatedwith the same numeral and description thereof is omitted.

[Film Member]

A configuration of a solid-state imaging device of the tenth embodimentis illustrated in FIG. 19. In the solid-state imaging device illustratedin FIG. 19, a first film member 81, a second film member 82, a thirdfilm member 83, and a fourth film member 87 are formed on the backsurface of the semiconductor base 11. The first film member 81 is formedon a region in which the first photodiode PD1 and the second photodiodePD2 are formed, and on the p-well 44 that is exposed from the sidesurface of the trench in the element separation section 77. The secondfilm member 82 is formed on the contact section 41 and on the contactsection 41, the potential barrier section 42, and the chargeaccumulation section 43 that are exposed from the side surface of thetrench. The third film member 83 is formed on the semiconductor base 11in the inter-pixel region 30. Further, the fourth film member 87 isformed on the first film member 81, the second film member 82, and thethird film member 83, and is formed to fill in the trench of the elementseparation section 77.

The first film member 81 may be preferably configured of a film having anegative fixed charge. The film having the negative fixed charge may bemade of a material described above in the first embodiment. The secondfilm member 82 may be preferably configured of a film having a negativefixed charge, as with the first film member 81. However, the second filmmember 82 may be preferably made of a material that has a negative fixedcharge amount that is smaller than that of the first film member 81. Byselecting such a film having the negative fixed charge for the secondfilm member 82, it is possible to suppress dark current in the verticaltransfer path 40.

The third film member 83 may be preferably configured of a film having anegative fixed charge as with the first film member 81. By having thenegative fixed charge, dark current from the surface of thesemiconductor base 11 is suppressed. Further, by causing the third filmmember 83 to have a refractive index that is higher than that of thefirst film member 81, generation of a charge in the inter-pixel region30 is suppressed, which makes it possible to suppress color mixture.Further, a material that is typically used as a wiring or an electrodein a semiconductor unit may be applied as the fourth film member 87.

As described above, the films having the negative fixed charges that aremade of different materials are allowed to be formed in the respectiveregions of the region on the photodiode PD, the inter-pixel region 30,the contact section 41, and the element separation section 77. Byforming the films having the negative fixed charges in all of theregions, it is possible to suppress dark current from the surface of thesemiconductor base 11. Moreover, by selecting the material, thethickness, the forming method, etc. so that the negative fixed chargeamount of the film member, the refractive index, etc. in the respectiveregions, suppression of dark current, suppression of color mixture, etc.are allowed to be achieved.

[13. Eleventh Embodiment of Solid-State Imaging Device]

Next, an eleventh embodiment of the solid-state imaging device isdescribed. It is to be noted that the eleventh embodiment describedbelow has a configuration similar to those in the first embodiment andthe ninth embodiment described above except for a configuration of filmmembers on the back surface of the semiconductor base 11. Accordingly,in the description below of the eleventh embodiment, a configurationsimilar to those in the first embodiment and the ninth embodiment isdesignated with the same numeral and description thereof is omitted.

[Film Member]

A configuration of a solid-state imaging device of the eleventhembodiment is illustrated in FIG. 20. In the solid-state imaging deviceillustrated in FIG. 20, a first film member 84, a second film member 85,and a third film member 86 are formed on the back surface of thesemiconductor base 11.

The second film member 85 is formed on the contact section 41, and onthe contact section 41, the potential barrier section 42, and the chargeaccumulation section 43 that are exposed from the side surface of thetrench. Further, the first film member 84 is formed on a region in whichthe first photodiode PD1 and the second photodiode PD2 are formed, onthe p-well 44 exposed from the side surface of the trench in the elementseparation section 77, and on the second film member 85. Further, thethird film member 86 is formed to cover a region, on the semiconductorbase 11, in which the first film member 84 is not formed, and a regionon the first film member 84.

The first film member 84 may be preferably configured of a film having anegative fixed charge. The film having the negative fixed charge may bemade of the material described above in the first embodiment. The secondfilm member 85 is formed of a material that has a small interface state.For example, the second film member 85 may be configured of an oxidefilm formed as a result of reaction with the material of thesemiconductor base 11, or the like. Further, the second film member 85is formed to have a thickness that does not give an influence, of thefirst film member 84 configured of the film having the negative fixedcharge, on the vertical transfer path 40. A material that is typicallyused as an interlayer insulating film of wiring layers in asemiconductor unit may be applied to the third film member 86.

The second film member 85 is formed on the contact section 41, andbetween the first film member 84 and the vertical transfer path 40exposed to the trench side surface in the element separation section 77.In other words, due to the second film member 85, there is achieved aconfiguration in which the vertical transfer path 40 and the first filmmember 84 are not in direct contact with each other. In thisconfiguration, the vertical transfer path 40 is not influenced by thefirst film member 84 configured of the film having the negative fixedcharge. Accordingly, it is possible to suppress generation of darkcurrent in the vertical transfer path 40. Further, by using the materialthat has a small interface state as the second film member 85, it ispossible to suppress dark current from the interface of the verticaltransfer path 40 covered with the second film member 85.

[14. Electronic Apparatus]

Next, description is provided of an embodiment of an electronicapparatus that includes the above-described solid-state imaging device.The above-described solid-state imaging device may be applicable, forexample, to an electronic apparatus such as a camera system, a mobilephone having an imaging function, or other device having an imagingfunction. Examples of the camera system may include a digital camera anda video camcorder. FIG. 21 illustrates, as an example of the electronicapparatus, a schematic configuration of a case where the solid-stateimaging device is applied to a camera capable of shooting a still imageor a moving image.

A camera 100 in this example includes a solid-state imaging device 101,an optical system 102, a shutter unit 103, and a drive circuit 104. Theoptical system 102 guides incident light to a light reception sensorsection of the solid-state imaging device 101. The shutter unit 103 isprovided between the solid-state imaging device 101 and the opticalsystem 102. The drive circuit 104 drives the solid-state imaging device101. Further, the camera 100 includes a signal processing circuit 105that processes an output signal of the solid-state imaging device 101.

The solid-state imaging device described above in any of the embodimentsand the modifications is applicable to the solid-state imaging device101. The optical system (an optical lens) 102 causes image light(incident light) from a subject to be formed as an image on an imagingsurface (not illustrated) of the solid-state imaging device 101. Thus, asignal charge is accumulated in the solid-state imaging device 101 for acertain period. It is to be noted that the optical system 102 may beconfigured of an optical lens group that includes a plurality of opticallenses. Further, the shutter unit 103 controls a light illuminationperiod and a light blocking period of incident light with respect to thesolid-state imaging device 101.

The drive circuit 104 supplies drive signals to the solid-state imagingdevice 101 and the shutter unit 103. Further, the drive circuit 104controls, with the use of the supplied drive signals, a signal outputoperation of the solid-state imaging device 101 to the signal processingcircuit 105, and a shutter operation of the shutter unit 103. In otherwords, in this example, a signal transfer operation from the solid-stateimaging device 101 to the signal processing circuit 105 is performedwith the use of the drive signal (a timing signal) supplied from thedrive circuit 104.

The signal processing circuit 105 performs various signal processes on asignal transferred from the solid-state imaging device 101. Further, thesignal (a picture signal) on which the various signal processes areperformed is stored in a storage medium (not illustrated) such as amemory, or is outputted to a monitor (not illustrated).

According to the electronic apparatus such as the camera 100 describedabove, it is possible to provide an electronic apparatus that hasimaging characteristics improved by the solid-state imaging device 101.

It is to be noted that, in the semiconductor imaging device describedabove, the second-conductivity-type FD region and thesecond-conductivity-type photodiode PD region are formed in thesemiconductor region of the first conductivity type, for example, of ap-type, that is formed on the semiconductor base of the secondconductivity type, for example, of an n-type. However, the conductivitytypes of the n-type and the p-type may be opposite in the presenttechnology. In this case, the signal charge transferred from thephotoelectric conversion film to the semiconductor base is considered asa hole, and the conductivity types of the n-type and the p-type of thevertical transfer path connected to the photoelectric conversion film ismade opposite.

It is to be noted that the present disclosure may also have thefollowing configurations.

(1) A solid-state imaging device including:

a semiconductor base;

a photoelectric conversion element provided in the semiconductor base;

a photoelectric conversion film arranged on a light receiving surfaceside of the semiconductor base;

a contact section to which a signal charge generated in thephotoelectric conversion film is read, the contact section beingprovided in the semiconductor base;

a first film member covering the photoelectric conversion element; and

a second film member provided on the contact section.

(2) The solid-state imaging device according to (1), wherein the secondfilm member is provided on the semiconductor base in an inter-pixelregion between the photoelectric conversion elements adjacent to eachother.

(3) The solid-state imaging device according to (1), further includingthe third film member on the semiconductor base in an inter-pixel regionbetween the photoelectric conversion elements adjacent to each other,the third film member being made of a material different from those ofthe first film member and the second film member.(4) The solid-state imaging device according to any one of (1) to (3),wherein the first film member has a configuration in which differenttypes of film members are laminated.(5) The solid-state imaging device according to any one of (1) to (4),wherein the second film member is laminated on the first film member.(6) The solid-state imaging device according to any one of (1) to (5),wherein the first film member includes at least one selected from a filmhaving a negative fixed charge, a semiconductor material having a bandgap larger than that of the semiconductor base, and a conductive layer.(7) The solid-state imaging device according to any one of (1) to (6),wherein the second film member includes at least one selected from afilm having a negative fixed charge amount smaller than that of thefirst film member, a film having an interface state smaller than that ofthe semiconductor base, and a conductive layer.(8) The solid-state imaging device according to any one of (1) to (7),further including an embedded-type element separation section around thecontact section.(9) The solid-state imaging device according to (8), wherein the firstfilm member is included in the element separation section.(10) The solid-state imaging device according to (8) or (9), wherein thesecond film member is included in a portion, in the element separationsection, that is in contact with the contact section.(11) A solid-state imaging device including:

a semiconductor base;

a photoelectric conversion element provided in the semiconductor base;

a first film member provided on the photoelectric conversion element;and

the second film member provided on the semiconductor base in aninter-pixel region between the photoelectric conversion elementsadjacent to each other.

(12) A method of manufacturing a solid-state imaging device, the methodincluding:

a step of forming a photoelectric conversion element and a contactsection in a semiconductor base;

a step of forming a first film member on the semiconductor base at aposition that covers the photoelectric conversion element;

a step of forming a second film member on the semiconductor base at aposition that covers the contact section; and

a step of forming a photoelectric conversion film on a light receivingsurface of the semiconductor base.

(13) An electronic apparatus including:

the semiconductor unit according to any one of (1) to (10); and

a signal processing circuit configured to process an output signal ofthe semiconductor unit.

(14) An electronic apparatus including:

the semiconductor unit according to (11); and

a signal processing circuit configured to process an output signal ofthe semiconductor unit.

This application claims priority on the basis of Japanese PatentApplication JP 2012-146499 filed Jun. 29, 2012 in Japan Patent Office,the entire contents of which are incorporated herein by reference.

It should be understood by those skilled in the art that variousmodifications, combinations, sub-combinations, and alterations may occurdepending on design requirements and other factors insofar as they arewithin the scope of the appended claims or the equivalents thereof.

The invention claimed is:
 1. A solid-state imaging device comprising: asemiconductor base; a photoelectric conversion film arranged on a lightreceiving surface side of the semiconductor base; a plurality of unitpixels, each of the unit pixels including: a first photoelectricconversion element provided in the semiconductor base; a bottomelectrode; a contact plug; a contact section electrically connected tothe bottom electrode by the contact plug, the contact section beingprovided in the semiconductor base; a first film member covering thefirst photoelectric conversion element; and a second film member,wherein the second film member extends between the first film member andthe bottom electrode of the plurality of unit pixels.
 2. The solid-stateimaging device according to claim 1, wherein the second film member isprovided on the semiconductor base in an inter-pixel region between thephotoelectric conversion elements of adjacent unit pixels.
 3. Thesolid-state imaging device according to claim 1, further comprising athird film member on the semiconductor base in an inter-pixel regionbetween adjacent unit pixels, the third film member being made of amaterial different from those of the first film member and the secondfilm member.
 4. The solid-state imaging device according to claim 1,wherein the first film member has a configuration in which differenttypes of film members are laminated.
 5. The solid-state imaging deviceaccording to claim 1, wherein the second film member is laminated on thefirst film member.
 6. The solid-state imaging device according to claim1, wherein the first film member includes at least one of a film havinga negative fixed charge, a semiconductor material having a band gaplarger than that of the semiconductor base, and a conductive layer. 7.The solid-state imaging device according to claim 1, wherein the secondfilm member includes at least one of a film having a negative fixedcharge amount smaller than that of the first film member, a film havingan interface state smaller than that of the semiconductor base, and aconductive layer.
 8. The solid-state imaging device according to claim1, further comprising an embedded-type element separation section aroundthe contact section.
 9. The solid-state imaging device according toclaim 8, wherein the first film member is included in the elementseparation section.
 10. The solid-state imaging device according toclaim 8, wherein the second film member is included in a portion, in theelement separation section, that is in contact with the contact section.11. A method of manufacturing a solid-state imaging device, the methodcomprising: forming a plurality of unit pixels in a semiconductor base,each of the unit pixels including: a first photoelectric conversionelement formed in the semiconductor base; a first film member coveringthe first photoelectric conversion element; a portion of a second filmmember that extends over the first film member of each of the pluralityof unit pixels; a bottom electrode, wherein the second film member isbetween the first film member and the bottom electrode; a contact plug;a contact section electrically connected to the bottom electrode by thecontact plug, the contact section being provided in the semiconductorbase; and a step of forming a photoelectric conversion film on at leastthe bottom electrode of each of the unit pixels.
 12. An electronicapparatus comprising: a semiconductor unit; and a signal processingcircuit configured to process an output signal of the semiconductorunit, the semiconductor unit including: a semiconductor base; aphotoelectric conversion film arranged on a light receiving surface sideof the semiconductor base; a plurality of unit pixels, each of the unitpixels including: a first photoelectric conversion element provided inthe semiconductor base; a bottom electrode; a contact plug; a contactsection electrically connected to the bottom electrode by the contactplug, the contact section being provided in the semiconductor base; afirst film member covering the first photoelectric conversion element;and a second film member, wherein the second film member extends betweenthe first film member and the bottom electrode of the plurality of unitpixels.